But one thing the CBP agents seem to encounter above all else is methylamine hydrochloride, a chemical used to make methamphetamines.

The latest seizure came earlier this month, agents announced today, as 5,700 pounds of the chemical -- several barrels’ worth -- were headed through LAX from China on their way to Mexico.

The Daily News reports that two shipments were intercepted on April 19 and 23. The chemicals theoretically could have been used to make roughly 3,600 pounds of meth -- worth about $40 million. They can also be used to make ecstasy.

Or they can be used for legitimate purposes. The CBP states that “Methylamine hydrochloride is a corrosive, flammable, strong odor chemical essential to manufacture methamphetamine and ecstasy. Methylamine hydrochloride has legitimate industrial applications in pesticides, solvents and pharmaceutical products.”

Whatever it’s made for, methylamine must be declared under the Controlled Substances Act -- and these shipments weren’t, CBP agents say.

U.S. Customs and Border Protection is an arm of Homeland Security tasked with regulating international trade. It is not the same as the Transportation Security Administration, or TSA, which recently drew negative attention after four of its officers were caught allegedly helping to smuggle drugs into the country through LAX.